On the design of electron guns for cyclotron resonance masers utilizing trochoidal electron beams (trochotrons)

The properties of crossed-field electron guns which are capable of providing the required trochoidal beams for efficient cyclotron resonance interaction in the trochotron configuration are analyzed. A discussion of the beam parameters that are used to characterize the device performance is included in a general description of the operation of these guns. Two concrete designs are presented and are used to demonstrate the performance capabilities of these devices with respect to the beam self-fields, the externally applied electric and magnetic fields, and the electrode geometry. It is shown that these devices, which typically generate beams with large ratios of perpendicular to parallel (drift) velocity, are capable of producing extremely small drift velocity spreads over a wide range of parameters.